Vacuum-tight seal.



P. G. KEYES.

VACUUM TIGHT SEAL.

APPLICATION FILED 11.1.3.6, 1913.

1,079,352. *Y Patented Nov. 25, 1913.

@8W wat Q s.. l w1 M jederdcjc .f e6, 4 J, f j i FREDERICK G. KEYES, OF BOSTON, MASSACHUSETTS,

ASSIGNQR TO'ARTHUR A. NOYES TRUSTEE, OF BOSTON, MASSACHUSETTS.

VACUUM-TIGHT SEAL.

Specification of Letters Patent. Application ledliarch 6, 19113. Serial N o. 762,318.

Patented Nov. 25, 1 913.

To all whom t may concern:

Be it known that I, FREDERICK G. Kants, a citizen ofl the United States and resident of Boston, in the county of Suffolk and State of Massachusetts, lhave invented new and useful Improvements in Vacuum Tight Seals, of which the following is a specification.

My invention relates to the construction of seals for vapor electric apparatus, and its object. is the provision of such a structure as shall be permanently gas-tight and reliable.

In vapor electric apparatus, of which the quartz (fused silica) mercury arc lamp is an example, the entire apparatus including seals, liquid, and vapor, is normally operated at an elevated temperat-ure. Under these conditions thc mercury becomes lnore activethan it is at ordinary temperatures and it amalgamates .metals which at ordinary temperatures are practically free from its action.

In aco-pending application (Serial No. 752316)filed concurrently with this application I have described a seal for vapor electric apparatus that is intended "for operation at elevated temperat-ures. This seal consists of a: thin tube of metal possessing considerable plasticity or ductility sealed through the wall of the non-conducting container, and a lea-d entering the container through or by means of themetallic tube. For the success of this seal it is necessary that the metallic tube shall retain its ductility or plasticity under all conditions of manufacture and operation. When the tube is constructed of platinum, for example, which is attacked by mercury at high temperatures, it is necessary to protect the tube against the action of the liquid or vapor within the container, namely, mercury in this instance, since I am speaking of a quartz mercury arc lamp by way of illustration. This protection against mercury I have secured as described in my said application, by interposing between the platinum tube and the interior of the container a barrier of yielding material, as pulverulent material such' as ferric oxid (FezOs). lSuch a material enormously retards the penetration of mercury or mercury vapor into the neighborhood of the platinum tube and thus enables me to apply this seal successfully under conditions where for example, a`

it would otherwise fail. I now find, and this constitutes an important element in my present invention, that by interposing between the interior of the container and the tubular metal member a material which combines with mercury, the rate of difusion of mercury into the neighborhood of the metal sealing tube may be still further retarded, since theva'pors are absorbed by the material in question as they very slowly penetrate the material.

I shall throughout the specification and claims employ the term absorbin material to designate any material whlch performs the function described above; it may for example be metallic copper.

My invention will be better understood by reference to the accompanying figures in which:

Figure l represents a sectional view of a seal embodying my invention; and Fig; 2 represents a sectional view of another seal, embodying my invention but differing from the iirst in certain details.

Referring now to Fig. l, A- is a tube of 4 non-conducting material which forms a part of the container into which current is to be introduced. By way of illustration I shall assume the container to be constructed of fused silica. B is a thin metal tube which may be platinum. C is a vitreous member which is sealed to the platinum tube B on the one hand, and tothe fused silica tube A on the other. D is alead welded or otherwise joined to one end of the tube B, which is closed, and extending inwardly into the container. In a quartz lamp the arc is usually assed through mercury vapor. To protect. t e tube B against the action of mercury, a material is interposed between B and the interior of the container to intercept the mercury or mercury vapor. As shown in Fig. l, the absorbing material is applied in the form of a fine powder, as for example, copper powder. Thus, the same material serves the double purpose of hindering the diffusion of mercury vapor by purely mechanical means while at the same time it absorbs the mercury vapor by alloying therewith and thus hinders the penetration of mercury vapor by arresting and absorbing the vapor which has penetrated. To keep the absorbing material E in place, a dia- 4'phragm F is provided. This diaphra m enlonce it has penetrated to the region in which the granules of absorbing Lmaterial E are located, the further penetration is still further retarded by the absorption of the vapor by the granules.

My invention is not restricted to the applicat-ion of the absorbing materia-l in any articular form such as granules or powder,

ut admits of application in other forms without departing from my invention. For example, the lead D itself may be constructed of a material which absorbs the vapors, the penetration of which into the neighborhood of the tube B is to be overcome.

If the life of the vapor-apparatus were indefinitely long (which it is not) the con tained vapor would eventually penetrate to the seal and deteriorate the metal member thereof, and impair or destroy its eliciency. But the function of the barrier material above described, in absorbing the gradually encroaching vapor and thus delaying its progress toward the seal, is effective to such an extent that the functional life of such an absorbent material (even though it be of moderate extent) is far in excess of the life of the vapor apparatus as a whole.

What I claim and desire to secure by Letters Patent is:

1. In a vapor electric apparatus, a container, a metallic member sealed through the wall of the container an absorbing material interposed between the interior of the container and the metallic member to dela the penetra-tion of vapor into the neighbor ood of thefmetallic member.

2. In a vapor electric a paratus, a container, a metallic lead sea ed through the Wall of the container, an absorbing material pulverulent in form, interposed between the interior of the container and the metallic member to delay the penetration of vapor into the neighborhood of the metallic member.

3. In a vapor electric apparatus, a container constructed of nonconducting mate rial, a metallic member passing through the wall of the container, an absorbing material embedded in a pulverulent material, interposed between the interior of the container and the metallic member.

Signed by me atBoston, Massachusetts, this twenty fifth day of February, 1913.

FREDERICK Gr. KEYES.

Witnesses:

ODIN ROBERTS, FLORENCE A. COLLINS. 

